This invention relates generally to an air moving fan device and, more particularly, an air moving fan device having an improved rotatable air deflector grill.
Generally, the airflow produced by a fan blade has two components. One is a linear component moving axially and caused by the pitch of a typical blade. The other is a circular component caused by the turbulence of the blade and its rotation. Together they create helically directed airflow that is commonly used to drive a rotatable grill and thereby change a fan's air discharge pattern. Prior fans of this type have exhibited various problems including complicated construction, inadequate control of grill rotation, fluctuating rotational grill speed, undesirable grill vibration, etc.
The object of this invention, therefore, is to provide a portable fan having an improved air driven protective grill for automatically and continuously changing the fan's air discharge pattern.